(1) Field of the Invention
The present invention relates to an NMR sample tube suitable for use in a nuclear magnetic resonance signal measuring device (NMR device).
(2) Related Art
A nuclear magnetic resonance signal measuring device applies an RF magnetic field to a sample to be measured to obtain nuclear magnetic resonance signals (NMR signals) from the sample. In order to increase the strength of the signal, the static magnetic field in the sample space is required to have high homogeneity.
Since the sample is precious, a minute sample is put in a thin sample tube to measure it. The sample is usually in a form of liquid. A difference between the magnetic susceptibility of the sample and that of objects around the sample lowers the homogeneity of the static magnetic field in the sample space. If the magnetic susceptibility changes stepwise at the portion where the sample abuts surroundings therearound as viewed from the direction of the applied static magnetic field, magnetic charge appears thereon, and thus a further magnetic field is generated so that the homogeneity of the magnetic field is lowered.
JP-A-10-332800 discloses that a material having the same magnetic susceptibility as the sample is arranged below the sample, the sample is placed thereabove, and a plug adjusted to have the same magnetic susceptibility as the sample is inserted above the sample to provide a symmetrical sample tube. The plug is constituted of a first plug having a through-hole for bubble removal and a second plug fitting in the first plug.
The object of JP-A-10-332800 is removal of bubbles generated in the sample portion.